WACO (AP) – A private ceremony is planned to mark the 20th anniversary of the botched raid on the Branch Davidians compound near Waco that left four federal agents dead.

The U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives on Thursday will honor agents Conway LeBleu, Todd McKeehan, Robert John Williams and Steven Willis. They died in the Feb. 28, 1993, gun battle that erupted when agents raided the compound of the religious group suspected of stockpiling weapons. Six Davidian members also died that day.

It was the beginning of a 51-day standoff that ended in the deaths of about 80 more sect members, including two dozen children.

Government investigations later criticized the ATF for not calling off the raid after learning that sect leader David Koresh had learned the plans.